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Pre and post 1954 twin clutch

richardb

Website User
Non-VOC Member
Can anyone help shed some light on the differences between the clutch shaft (G3), carrier (C3) and retaining nut (C20) for the pre and post 1954 twin clutch ?

Whatever the differences are determine which version of C18 is used.

Richardson says; "In 1954 a rubber O ring was introduced to take the place of the bonded carrier seal, but this requires a different pattern clutch shaft (G3/1AS), carrier (C3/2) and retaining nut (C20/1)" See Fig 33 and 36 in Richardson.
This is also covered in Know Thy Beast Chapt 11, 3rd para of section "The Shoe Carrier, Main Nut and Seal". Here Stevens says the O ring can be used with the earlier components if a steel ring is used as a spacer but still the newer version C3/1 and C20/1 would be needed. Or, he even says that, the O ring and Light alloy seal can be used together.

From the spares list;
C18/1 = Early type light alloy.
C18/2 = 1954 and after O ring and is used with G3/1AS, C3/2 and C20/1

So the question is how can you differentiate the 1954 components of; clutch Shaft G3/1AS, carrier C3/2 and retaining nut C20/1 from the earlier versions which I assume are G3, C3 and C20 ?

Are there any dimensional differences ?, or pattern differences ? or other ?

Thanks in advance,
Richard
 

Vic Youel

Well Known and Active Website User
Non-VOC Member
Clutch C18 size

This issue has always puzzled me too. I would particulary like to discover the correct thicknesses of the C18/1 and 2 seals/washers. In the past I have purchased these and found they come in differing sizes.

It occurs to me that technical drawings committee may have the answers. So hopefully someone in the know can provide the answers.

Vic
 

BlackLightning998

Well Known and Active Website User
VOC Member
And remember those spacing washers on later bikes too....

Richard,

Also I don't think the books and drawings show the additional spacing washers that should be fitted to get the clutch working perfectly without any drag or fouling - I don't recall exactly which ones and where - I only know that when John Coates stripped my clutch they were missing and there were rubbing/interference marks inside. I'm sure someone on the Forum can tell you what part number and where to fit them - I recall 3 in number.

Stuart


This issue has always puzzled me too. I would particulary like to discover the correct thicknesses of the C18/1 and 2 seals/washers. In the past I have purchased these and found they come in differing sizes.

It occurs to me that technical drawings committee may have the answers. So hopefully someone in the know can provide the answers.

Vic
 

Vic Youel

Well Known and Active Website User
Non-VOC Member
Clutch washers

Thanks Stuart,

That prompted me to look out my copy of the set of instruction sheets that sometimes become available. I suspect they were issued by Harpers in the seventies.

Referring to sheet number 2D at the top of page 9 it refers to the 6 washers.

Richard, I'll bring the notes along tonight; the one on clutch assembly is extremely comprhensive and you are welcome to borrow the notes.

I would think you can still purchase copies from the usual sources.

Cheers

Vic
 

Hugo Myatt

Well Known and Active Website User
VOC Member
In KTB page 121 under Clutch Drag (e) refers to six washers ET98/1. These are placed over the pins before offering up the inner clutch plate. Only six are used as the pins are too close together to fit nine.
At one time Tony Maughan produced a special seal C18/?. It was an alloy spacer with an O ring on the outer periphery. This was thicker than the original C18/1 and required a slightly shortened C20. Some of these shortened C20s still turn up and will lock up the whole assembly if used with a standard C18/1
 

timetraveller

Well Known and Active Website User
VOC Member
Some of the confusion might arise from the pre and post series 'D' drawings in the official Vincent spares sheets. The gearbox mainshaft is drawn as the same item in the two copies which I have (other copies might differ) whereas in reality the two items are very different. On the later models the outer (clutch) end of the mainshaft is cylindrical without the splines going all the way to the end. You have to use the correct retaining nut with each type of shaft or it just will not fit.

Regarding 'o' ring seals etc, I have mentioned in these pages earlier about putting an 'o' ring at the inner edge of the shoe carrier C3 after the inner edge of this has been chamfered or counter bored. It stops the oil getting into the shaft, rather than trying to stop it getting out and one just does not have to mess about with seals or jointing compound at the other end. If you have not done this yet you will be amazed at just how much better the whole system is. :)
 
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